Re: [core] Modernized Link Format

Jim Schaad <ietf@augustcellars.com> Sun, 21 October 2018 16:33 UTC

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From: Jim Schaad <ietf@augustcellars.com>
To: 'Klaus Hartke' <hartke@projectcool.de>, =?utf-8?Q?'Christian_M._Ams=C3=BCss'?= <christian@amsuess.com>
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Date: Sun, 21 Oct 2018 09:32:31 -0700
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Subject: Re: [core] Modernized Link Format
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Would it be possible to get a link to CoRAL as I don't think I have ever seen it.

> -----Original Message-----
> From: core <core-bounces@ietf.org>; On Behalf Of Klaus Hartke
> Sent: Sunday, October 21, 2018 9:04 AM
> To: Christian M. Amsüss <christian@amsuess.com>;
> Cc: core@ietf.org WG <core@ietf.org>;
> Subject: Re: [core] Modernized Link Format
> 
> Christian Amsüss wrote:
> > The last state I know are our discussions from March, since which
> > representations (formerly fat links) have been re-introduced.
> >
> > Has CoRAL received any reviews since then? Is it progressing towards
> > adoption by T2TRG?
> 
> Adoption is now on the agenda of the T2TRG summary meeting in Bangkok
> [1]. The draft hasn't seen any significant reviews since March, though.
> 
> > Would we need to / should we, if the RD were to forego fixing RFC6690
> > and rely on CoRAL to express what can't be said with link-format, do
> > in terms of implementation limits and profiles? Should there be a
> > dedicated profile for "CoRAL used as link-format replacement", or
> > would you expect the default profile to work here?
> 
> While the default profile technically works, it's not as efficient as it can get
> since it doesn't assign numeric identifiers, e.g., to the "hosts" relation type
> and RFC 6690 link attributes. So there should be a profile that does for "Link
> Format in CoRAL" what
> draft-ietf-core-links-json-10#section-2.3 [2] does for "Link Format in CBOR".
> I don't know if that has to be a profile that is dedicated to this application or
> if it'd make sense, for example, to have a general "CoRE Profile" that works
> also for /.well-known/core and other CoRE WG specifications.
> 
> > Are there yet examples of a
> > .well-known/core file expressed in CoRAL?
> 
> Here's one example from RFC 6690 [3] expressed in CoRAL:
> 
> OLD:
> 
> </sensors>;ct=40;title="Sensor Index",
> </sensors/temp>;rt="temperature-c";if="sensor",
> </sensors/light>;rt="light-lux";if="sensor",
> <http://www.example.com/sensors/t123>;anchor="/sensors/temp";rel="des
> cribedby",
> </t>;anchor="/sensors/temp";rel="alternate"
> 
> NEW:
> 
> #using <http://www.iana.org/assignments/relation/>
> #using lf = <http://TBD/>
> 
> hosts </sensors> {
>     lf:ct "40"
> }
> 
> hosts </sensors/temp> {
>     lf:rt "temperature-c"
>     lf:if "sensor"
>     describedby <http://www.example.com/sensors/t123>
>     alternate </t>
> }
> 
> hosts </sensors/light> {
>     lf:rt "light-lux"
>     lf:if "sensor"
> }
> 
> > I'm all for the approach, but at what time frame can it be realized,
> > and
> 
> I think it'd make sense to have at least one or two interop events, so it
> depends on how quickly the draft gets adopted, implementations created,
> interoperability confirmed, reviews done.
> 
> While I think the draft is already in quite a good state, I would probably
> rather lean towards getting it right than rushing it out.
> 
> > which working groups will need to be involved at which stage to avoid
> > surprises at IESG review? (Eg. equating target attributes with literal
> > properties under http://TBD/ is something that could need feedback
> > from RFC8288's WG^Wauthors^H or other RDF-using WGs.)
> 
> RFC 8288 gives some license to deviate from the spec where it makes sense
> in different link serialization formats. For example,  Atom allows IANA-
> registered link relation types to be serialized as URIs using the prefix
> "http://www.iana.org/assignments/relation/", which is specific to Atom (and
> adopted by CoRAL) and not part of RFC 8288 [4].
> So I don't think there's a hard dependency on feedback from the RFC
> 8288 authors. Review from the RFC 8288 authors and other working groups
> would be welcome, of course.
> 
> One thing that could raise eyebrows is if the CoRE WG started to assign
> numeric identifiers to all IANA-registered link relation types [5]. I thought of
> doing that in draft-hartke-core-apps-07 [6], but am now not so sure if that is
> the right path.
> 
> Does anything else come to your mind that could lead to surprises at IESG
> review?
> 
> Klaus
> 
> [1] https://github.com/t2trg/2018-ietf103
> [2] https://tools.ietf.org/html/draft-ietf-core-links-json-10#section-2.3
> [3] https://tools.ietf.org/html/rfc6690#page-14
> [4] https://tools.ietf.org/html/rfc8288#appendix-A.2
> [5] https://www.iana.org/assignments/link-relations/link-relations.xhtml
> [6] https://tools.ietf.org/html/draft-hartke-core-apps-07#section-6.2
> 
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